With the advent of "intelligent" fax machines having more sophisticated processors and memory, fax machine vendors have enhanced their fax machines to include an array of additional features. Such features include inbound routing via e-mail addresses, multi-hop relay, relay security, binary file transfer, etc. While these additional features improve the functionality of the fax machine, they also create a compatibility problem because each fax machine vendor may have a unique way of supporting them. Fax machine vendors have extended the "Group 3" facsimile transmission standard to support their additional features.
To understand the nature of the compatibility problem, it is helpful to first provide a background on the facsimile transmission standards. Most fax machines today conform to the Group 3 facsimile transmission standard. Established by the Comite Consultatif Internationals de Telegraphie et Telephonie (CCITT), Group 3 is one of the four groups defining facsimile transmission standards and is designed for digital data transfer over an ordinary telephone line. Within the Group 3 standard, there are various recommendations that relate to aspects of facsimile transmission. Recommendation T.4 defines a data compression standard, while Recommendation T.30 defines a protocol standard. In general, the Group 3 standard supports "standard" and "fine" images, two methods of data compression, password protection and polling. Office machines developed to communicate using the Group 3 standard are called "Group 3 office machines."
The T.30 protocol includes five phases of facsimile transmission: A) a call set up phase that includes establishing a call between a calling and receiving device; B) a pre-message phase that includes identifying and selecting data encoding and processing capabilities; C) a message transmission phase that includes transferring data, synchronization, error detection and correction, and line supervision; D) a post message phase that includes signalling the end of the message and confirming the message; and E) a call release phase that includes terminating the call.
During phase B, the calling and receiving devices exchange information to identify themselves and their capabilities. The receiving device transmits a digital identification signal (DIS) describing its data encoding and processing capabilities. The DIS characterizes the receiving device's standard CCITT capabilities. The receiving device may also send a Called Subscriber Identification (CSI) frame to provide its specific identity by its international telephone number. Finally, the receiving device may send a Non-Standard Facilities (NSF) data frame to identify the so-called "non-standard facilities" such as user identification information, passwords, and facsimile relay. The calling device sends various signals in response. The calling device sends a Digital Command Signal (DCS) responding to the standard capabilities identified by the DIS signal. The calling device may also send a Non-Standard facilities Set-up (NSS) signal in response to information contained in the NSF frame.
To support additional feature sets, fax machine vendors have extended the standard T.30 protocol and have developed unique NSF frames. Because vendors have unique NSF frames and have created their own versions of the T.30 protocol, a fax machine must be able to interpret the NSF frame and support the proprietary protocol implementation of another machine to fully take advantage of features available on the other machine. To solve this compatibility problem, it is necessary to develop a method for making a fax machine compatible with a number of protocol implementations.
Fax machines have been made to support non-standard facilities of another fax machine, but until this invention, a method has not been developed for easily modifying a fax machine to support feature sets of various fax machine vendors. Moreover, there exists no general way to increase the compatibility of a fax machine such that it may support any number of feature sets from various vendors.
There is thus a need for a fax machines that can support the non-standard features of a number of other fax machines. There is also a need for a way to improve fax machine compatibility that generally applies to today's intelligent fax machines. Finally, there is a need to provide a method to make it easier to add support for feature sets to a fax machine as different protocols are developed.
The object of the invention, therefore, is to provide a fax machine that is compatible with a number of fax machine protocols and also supports a broad range of fax capabilities.
Another object of the invention is to provide method for increasing the compatibility of a fax machine that is generally applicable to fax machines of various vendors.
Yet another object of the invention is to provide a fax machine that may be easily modified to increase its compatibility with other machines and to provide a method for doing so.
To achieve these objects, the invention provides a method and system for increasing the compatibility of a fax machine with other fax machines and protocols. Typically incorporated into a fax machine, the method enables a fax machine to support a number of feature sets and their corresponding fax protocols. The method includes determining whether a second fax machine is compatible with the protocols supported in the fax machine. If the second fax machine is compatible, the method includes selecting a compatible protocol implementation based upon information provided by the second fax machine. The method may also include interpreting information describing the capabilities of the second fax machine and mapping this information into a capability object.
The system of the invention includes a protocol module, at least one compatibility module, and a messaging protocol module. In one embodiment of the invention, the protocol module may select a compatibility module based on information provided by a second fax machine during a telephone call. If a compatibility module is selected, the compatibility module interprets this information and builds a capability object from it. The compatibility module transfers the capability object to the messaging protocol module, which reads this object and determines which capabilities may be used in communicating with the second fax machine. Fax data and information about the fax such as the size of the fax message, type and number of recipients, image resolution, etc. may be transferred to the messaging protocol module using a message object. Both the protocol module and the compatibility module may communicate with the messaging protocol module using message and capabilities objects.
The invention provides several advantages. Using compatibility modules, vendors can overcome the compatibility problem caused by the variety of non-standard features that other vendors have implemented in unique ways. Vendors can provide support for their protocols by building compatibility modules without disclosing proprietary information. By adding compatibility modules to new intelligent fax machines, vendors can build intelligent fax machines that support non-standard features of a variety of other machines. Compatibility modules are very efficient because they can take advantage of proprietary techniques of a vendor and, at the same time, use a set of message functions, external to the compatibility module, to handle basic message processing functions.
The invention also allows a fax machine to support more non-standard features in addition to those associated with compatibility modules loaded in the machine. The invention may include a fax protocol module, separate from the compatibility modules, supporting additional features not available in the compatibility modules. The fax protocol module can be used to support additional features used during communication with other fax machines supporting a compatible protocol.
Regardless of the protocol used to transfer a message, the invention provides a common interface between the messaging protocol module that processes messages and the underlying protocol modules that are used to transfer messages. This common interface comprises message and capabilities objects. These objects provide a well-defined interface that enables the intelligent fax machine to support various protocols. Because of this well-defined interface, vendors can more easily build compatibility modules. In addition, all of the peculiarities of a given protocol may be absorbed in protocol modules. The messaging protocol module deals only with the message and capabilities objects, not the details of the underlying protocols.
Further advantages and features of the invention will become apparent to those skilled in the art from the following description and accompanying drawings.